The beam test for the Shintake monitor succeeded in measuring signal modulation with the laser interference fringe pattern in November 2009. We have studied the error sources, and evaluated the systematic error to be less than 30% for 1 minute measur
ements. This paper centers on the evaluation of the Shintake monitor performance through analyzing beam tests deta. Most systematic error sources are well understood, enabling accurate measurement of the beam size when it reaches 37 nm.
